Crustal structure and origin of the Cape Verde Rise
Crustal structure and origin of the Cape Verde Rise
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DOI：
10.1016/j.epsl.2008.05.012
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发表时间：
2008-07-30
影响因子：
5.3
通讯作者：
Krabbenhoeft, A.
中科院分区：
文献类型：
--
作者：
Pim, J.;Peirce, C.;Krabbenhoeft, A.
佛得角群岛位于板块中部隆起的地形上，被认为是在深地幔柱之上形成的。广角地震数据已被用来确定沿着群岛440公里长的样带的地壳和上地幔结构。模型显示，“正常”的海洋地壳，厚度约为7公斤，存在于岛屿之间，由于火山负荷而轻微弯曲。没有直接证据表明下地壳中存在高密度体或上地幔存在异常低密度体。观测到的挠曲和自由空气重力异常可以用火山载荷解释，有效弹性厚度为30 km，载荷和填充密度为2600 kg m（-3）。佛得角涌浪的起源鲜为人知。预计在岛屿下方类似于125 Ma的海洋岩石圈的弹性厚度为30 km，这表明观测到的膨胀高度和高热流不能归因于岩石圈的热再加热。下地壳的高密度和速度和上地幔的低密度和速度的证据的缺乏表明，地壳底板或枯竭的膨胀根都不是造成水深比预期浅的原因，相反，膨胀是由与下地幔柱相关的动态隆起支撑的。(C) 2008 Elsevier B.V.版权所有
The Cape Verde Islands are located on a mid-plate topographic swell and are thought to have formed above a deep mantle plume. Wide-angle seismic data have been used to determine the crustal and uppermost mantle structure along a similar to 440 km long transect of the archipelago. Modelling shows that 'normal' oceanic crust, similar to 7 kin in thickness, exists between the islands and is gently flexed due to volcano loading. There is no direct evidence for high density bodies in the lower crust or for an anomalously low density upper mantle. The observed flexure and free-air gravity anomaly can be explained by volcano loading of a plate with an effective elastic thickness of 30 km and a load and infill density of 2600 kg m(-3). The origin of the Cape Verde swell is poorly understood. An elastic thickness of 30 km is expected for the similar to 125 Ma old oceanic lithosphere beneath the islands, suggesting that the observed height of the swell and the elevated heat flow cannot be attributed to thermal reheating of the lithosphere. The lack of evidence for high densities and velocities in the lower crust and low densities and velocities in the upper mantle, suggests that neither a crustal underplate or a depleted swell root are the cause of the shallower than expected bathymetry and that, instead, the swell is supported by dynamic uplift associated with the underlying plume. (C) 2008 Elsevier B.V. All rights reserved.